Automotive gauges commonly use an air core movement involving a permanent magnet armature and electrical coils for positioning the armature and an associated pointer according to the value of on input parameter. The input parameter is provided by an input control comprising a temperature sensor, a fuel level sender, etc. A gauge circuit having terminals for battery voltage, ground, and the input control varies the energization of the coils in a manner to produce a resultant magnetic vector which positions the pointer in accordance with the parameter value.
Unless special provision is made, such gauges have no position preference when the gauge energization is turned off, and the pointer will float or remain in its position at the time the circuit is disabled. This condition is aesthetically undesirable since it may give the impression that the gauge is operating incorrectly. A position preference can be provided, however, to establish a "zero" position or rest position, which may be the same as the zero value (or the lowest value) of the input parameter.
It has been proposed to add components to such a gauge to cause the pointer to automatically seek a rest position when the circuit is deenergized. For example it is possible to attach a magnet to some portion of the gauge structure to attract the pointer or the gauge armature to the rest position. Any such addition to the gauge adds expense to the manufacture of the gauge since both the extra component and the process of assembling it involve extra expense.